Evaluation of Watershed Carrying Capacity on Flood Management in Greater Malang East Java Indonesia

Abstract

Purpose: The over-depletion of natural resources in the Ambang watershed is the recent cause of the flooding in the region. The Ambang watershed, located in the larger Malang region of Indonesia's East Java Province, is the subject of this article because of the importance of this resource to local residents.This study follows the rules set out by Regulation No. P.61/2014 of the Indonesian Ministry of Forestry, which governs the assessment and monitoring of watershed management, in order to determine the Ambang watershed's effectiveness. Finding out how much water the Ambang watershed can hold and how well the regulation works to control floods were the two main goals of this research   Method: This study primarily uses data on floods, conservation initiatives, land use, and water value in the Ambang river basin. Data and information on floods, conservation regulations, and the worth of water infrastructure comes from government sources and community discussions. The data on land usage was derived from the analysis of satellite images. Literature reviews and reports from key government agencies (such as the regional agricultural agency, the regional environmental protection agency, and the district government) were used to gather secondary data for the Ambang watershed management study   Results and Conclusion: Land cover, as a percentage, can reduce run-off rates and enhance infiltration capacity in a watershed, hence monitoring it is crucial for assessing the state of land carrying capacity. With an area of 86,783.77 ha, the Ambang sub-watershed has 27,311.79 ha of vegetative land cover (PPV), which is classed as poor, falling between 20 and 40%. The result is expressed as a percentage. One way to measure the difference between allowed and actual erosion is via the Erosion Index. Based on the analysis, the Ambang sub-watershed, which covers an area of 86,783.77 ha, experiences heavy erosion on average with 190.8 tons/ha/year. The erosion index is 14.2, and the IE classification is > 2, which is very bad. This is due to factors such as steep to very steep slopes in some areas, poor to moderate soil conservation, and the presence of annual plants on the land, with some exceeding 25%.   Research Implications: In order to better educate the public about the conservation and restoration efforts of different stakeholders and to improve the recommendations for potential conservation and restoration actions in each of the Ambang watershed regions, a series of investigations and experimental projects are planned. Laws enacted by the Indonesian government (number 37/2012) and the Ministry of Forestry (number 6061/2014) control the administration of water-related regions in the country. Before receiving any funds from the National State Budget, regional (provincial) governments must develop a management plan that takes into account the watershed's ability to sustain initiatives. Our investigation showed that Regulation 61/2014, issued by the Federal Forestry Minister, does not adequately evaluate the Ambang watershed's harbor capacity. Especially in arid regions, further studies should help Indonesian watersheds better gauge the potential of their water supplies.